Mold for casting rolls.



J. L. LEWIS. MOLD FOB. CASTING ROLLS. 'uruoumn FILED JUNE 16,1906.

934,41 0. Patented Sept. 14, 1909.

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JOHN L. LEWIS, OF PITTSBURG, PENNSYLVANIA.

MOLD FOR CASTING ROLLS.

Original application filed January 24, 1906, Serial No. 297,707.

1906. Serial No. 321,976.

Specification of Letters Patent.

Patented Sept. 14, 1909.

Divided and this application filed June 16,

To all whom it may concern:

Be it known that I, JOHN L. LEWIS, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, a citizen of the United States, have invented or discovered a certain new and useful Improvement in Molds for Casting Rolls, of which improvement the following is a specification.

Chilled rolls are formed in molds consisting of three parts or members, a cope formed of sand loam having a matrix for the journal at one end of the roll, a drag also formed of loam sand and having a matrix for the other roll journal and also having the necessary sprues or passages for the inflow of molten metal, and one or more chilling cylinders formed of cast iron and arranged between the cope and drag. These chilling cylinders which are now made with a uniform thickness of wall are provided at their ends with radial lugs which are sometimes continuous forming laterally projecting flanges as shown in Figure 1. As these lugs or flanges are employed only for the purpose of connecting the chilling cylinders to the cope and drag and to other chilling cylinders when two or more such cylinders are employed, they are made of only sufiicient thickness to afiord the desired strength and rigidity for coupling the several parts together. The mold constructed as described is arranged vertically and the molten metal enters through the drag rising up through the latter, and the chilling cylinder to the cope. As the molten metal comes into contact with the almost cold metallic surface of the chilling cylinders a thin skin or shell is formed on and completely inclosing the mass of molten metal which when cold will form the roll and the chilling cylinders become heated and expand proportional to the degree of heating.

I have found that the chilling cylinders are subjected during the casting of the roll to some force which tends to cause a peripheral enlargement of the cylinders, the enlargen'ient being greater at the ends. This enlargement produced during the casting does not entirely disappear in the mold heretofore used after a casting has been made, but the end portions are permanently enlarged. As this enlargement occurs after each casting it results that although each increment of enlargement is small the cylinders will soon assume an hour-glass shape. This expansion of the cylinders seems to be due to an irregular heating of the cylinders or to an ununiform action of the heat on the cylinder. Whatever may be the cause of irregular expansion of the chilling cylinders and the incremental enlargement of the ends thereof, the de-formation of the cylinders causes a considerable loss in defective castings. As the thin shell formed on the roll surface on contact of the molten metal. with the chilling cylinder will be kept in a highly heated condition by the fluid interior of the casting, it will have but little strength, so that when the ends of the chilling cylinder expand outwardly leaving the thin skin or shell unsupported laterally or crosswise the pressure of the fluid column will cause a bulging and very frequently a rupture of this shell diametrically on a plane with the enlarged end portions .of the cylinder. WVhere two or more chilling cylinders are employed the double bulging diametrically on a plane with the adjacent ends of the chilling cylinders seems to subject the thin shell to such longitudinal strains that the ruptures are peripheral.

The present invention has for its object an equalization of the rate of expansion of all parts of the chilling cylinder or cylinders, thereby maintaining a lateral support at all points for the thin shell or skin first formed by contact of the molten metal with the chilling cylinders. This equalization may be attained either by retarding the expansion of the end portions of the chilling cylinders or accelerating the rate of ex pansion of the waist portion or portions of such cylinders by the application of heat thereto. The invention is hereinafter more fully described and claimed.

In the accompanying drawings forming a part of this specification Fig. 1 is an enlarged sectional view of the form of chilling cylinder now in use but having the thickness of wall at its waist reduced in thickness; Figs. 2, 3 and 4: are sectional views of difi'erent forms of chilling cylinders embodying my improvement, and Fig. 5 is a sectional elevation showing two chilling cylinders of the form shown in Fig. 2 arranged together for the production of a long roll.

In the practice of my invention I provide means whereby the expansion of the ends of the chilling cylinder may be retarded or that of the waist or middle portions of cylinders may be accelerated, such retardation or acceleration being so regulated that the rate of expansion shall be the same or substantially the same at all points of the cylinders. The retardation or acceleration may be effected in many ways, as by the application of a cooling or heating medium to the respective portions of the chilling cylinders as now constructed or by proportioning the thickness of the wall of the chilling cylinder at certain points. This latter method which may be carried out either by reducing the thickness of the wall at and adjacent to the waist of the cylinders as shown in Fig. 1, or by increasing the thickness of the end portions of the cylinders, is for many reasons preferred, and of these two alternative steps the increasing of the end portions of the cylinders is preferred.

As shown in Figs. 2, 3, 4c and 5, the required thickness of wall at the ends of the chilling cylinders can be attained by increasing the thickness and radial extension of the flanges 2 at the ends of the chilling cylinders. The amount of metal thus added at the ends and adjacent portions of the cylinders is such that by the time the heat from i the molten metal has difiused equally through the end portions, the waist portion will have been raised to the same temperature, and the expansion due to such heating will be the same at all points, and the relative internal dimensions will be preserved 1 which is the purpose of the invention. As 5 shown in Figs. 2 and 5 the added metal may i project with considerable abruptness from: the body of the cylinder or may extend with 1 a more or less gradual decrease in thickness toward the waist of cylinder as shown in Figs. 3 and 4. In the construction shown in I Figs. 2, 3 and 4c the added metal which is largely in excess of that required for chilling purposes is disposed in massive flange form and clamps can be readily applied thereto, as is the present practice, for 0011- necting the chilling cylinder to the cope and 1 drag and to another cylinder when two or ,1 more are required. When the metal is added as to form a wall gradually decreasing in thickness toward the waist, notches 3 are' provided for the reception of the ends of; the clamps. 1

As shown in Fig. l the chilling cylinders now in use can be so altered as by decreasing the thickness of the wall of the waist portion, as to insure a practically equal rate of expansion of all portions of the cylinder.

The retardation of the expansion of the ends of the cylinders can be effected by applying a cooling fluid to such portions, and an acceleration of the expansion of the waist of the cylinder can be had by applying a heating medium as gas jets to such waist portion.

Practical use of my invention has shown that by properly proportioning the thickness of the metal at the ends and waist portions of the chilling cylinder or cylinders the rates of expansion will bepractically the same at all points and the chilling cylinder or cylinders will retain their cylindrical shape and hence there will not be any bulgor swelling out of any portion of the roll formed in such mold.

No claim is made to the method of casting rolls described herein, as the same forms the subject matter of an application Ser. No. 297,706 filed January 24th, 1906, of which application this case is a division.

I claim herein as my invention:

1. A chilling cylinder for casting rolls having its walls so proportioned as regards thickness that the relative internal diametrical dimensions of the cylinder may-be preserved during the casting and cooling of the metal. i

2. A chilling cylinder for casting chilled rolls having at and adjacent to its ends an external thickness of metal, such thickness extending from its end along a substantial portion of the length of the cylinder whereby the internal diameters of the cylinder may be maintained at their normal relative values during the casting and cooling of metal therein.

3. A chilling cylinder for casting rolls having a greater thickness of wall at and adjacent to itsends and at its waist portion, the thickness of such wall gradually decreasing toward the waist portion with reference to preventing ununiform enlargement of the internal dimensions of the cylinder.

at. A chilling cylinder for casting rolls having its walls so proportioned as regards thickness as to prevent the permanent enlargement of the ends of the cylinder by use.

In testimony whereof, I have hereunto set my hand.

JOHN L. LEl VIS. Witnesses IIARRY L. Moore, E. I. ZINN. 

